Transistor regulators



, Nov. 5, 1963 I R E, D, ANDERSON I 3,109,982

- TRANSISTOR REGULATORS Filed Oct. 27. 1960 //v ve/v TOR R. E. D. ANDERSO/V A TTORNEV attenuating properties of the regulator.

This invention relates to transistor regulator circuits and, moreparticularly, to series transistor negative regulator circuits.

United States Patent Voltage regulators commonly employ p-n-p germaniumI transistors as series regulating devices because of their powerhandling capability. Germanium transistors of the n-p-n type arerestricted to power levels below one watt. Although high power n-p-nsilicon transistors are available, they are inefficient as seriesregulators because of their relatively high saturation resistance.

In certain negative voltage regulators it is necessary to connect theseries regulating transistor in' the negative lead. For example, when athree-leg (positive, negativepositive, negative) rectifier power supplysource is used,

' it is often desirable to use dual circuitry, i.e., positive and Thisis also necessary where negative voltage regulators. two or morenegative transistor regulators are operated in parallel from the samerectifier. The above-discussed transistor restriction necessitates theuse of p-n-p transistors which, in turn, present a biasing problem, whenthe-series regulating transistor must be connected in the negtaive leadof a negative voltage regulator. The series transistor biasing resistorin such a configuration absorbs input voltage variations therebyintroducing degeneration which, in turn, degrades the line regulatingand ripple In addition, the power dissipation of an associatedamplifier-detector network is increased.

It is. therefore, an object of this invention to provide efiicientnegative voltage regulators.

Another object of this invention is to provide a negative voltageregulator in which degeneration in the series transistor biasingresistor is reduced to a negligible value.

It has been found that these objectives may be achieved by employing anadditional low-power transistor shunted across the regulator'inputterminals.

. A feature ofthis invention resides in the use of a lowpower transistorto step down input voltage variations by a value equal to the gain ofthe said additional transistor stage. v, 7

Other objects and features of the present invention will become apparentupon consideration of the following detailed description and theaccompanying drawing, the single FIGURE of which is a schematic view ofa negative voltage regulator embodying the present invention.

Referring now to the drawing, there are provided direct-current inputterminals 22 and 23 and direct-current output terminals 24 and 25.Transistor 2 is an n-p-n transistor while transistors 1, 3 and 4 arep-n-p transistors.

V Transistor 1 is capable of passing large currents, while transistors2, 3 and 4 are capable of passing only small currents. Also provided areresistors 5, 6, 7, 8, 9, 10, 11, 12'. and 14, adjustable resistor 13,capacitors 15, 16 and 17 andasymmetrically conducting devices 18, 19, 20and 21.

An unregulated unidirectional voltage of the noted polarities is appliedto input terminals 22 and 23. The emitter electrode of n-p-n transistor2 is connected to the input terminal 23, while the collector electrodeof transistor 2 is connected to the input terminal 22 by resistor "ice 2a of transistor 2. The base electrode of transistor 1 is also connectedto input terminal 22 by resistor 6. The emitter electrode of transistor1 is connectedto output terminal.

25, while the collector electrode of tnansistor 1 is connected to inputterminal 23 by asymmetrically conducting device 20. The base andcollector electrodes of transistor 1 are connected together byasymmetrically conducting device 19. The collector electrode of p-n-ptrantransistor 3 to input terminal 22.

8 to output terminal 25. Resistor 9 and capacitor 17 connect the baseelectrode of transistor 3 to output terminal 25. The base electrode oftransistor 3 is also connected to the collector electrode of p-n-ptransistor 4 which is connected, in turn, to output terminal 25 byresistor 11. The emitter electrode of transistor 4 is connected to theoutput terminal 24 by asymmetrically conducting device 21 and to outputterminal 25 by resistor 10. Output terminal 24 is connected to outputterminal 25 by a serial connection comprising resistor 12, adjustableresistor 13 and resistor 14. The base electrode of transistor 4 isconnected to adjustable resistor 13. Gapacitor 16 connects the junctionof resistors 13 and 14 to output terminal 25. Capacitor 15 connectsoutput terminals 24 and 25.

It should be understood that, except for the series regu latingtransistor, combinations of p-n-p and n-p-ntransistors other than thosediscussed inthe foregoing description can be used equally aseffectively.

The operation of the regulating arrangement can be and a portion ofadjustable resistor 13 will appear at the base electrode of transistor4. The rise in positive potential at the base electrode of transistor 4causes more current to flow in the collector-emitter path of transistor4. This increased current flow causes the potential drop across resistor11 to increase thus decreasing the collectoremitter current flow intransistor 3. The decreased collector-emitter current flow of transistor3 causes the potential drop across resistor 5 to decrease which, inturn, decreases the collector-emitter current flow of transistor 2. Thedecreased collector-emitter current flow of transistor 2 causes thepotential'drop across resistor 6 to decrease. Since the bias potentialof transistor 1 is the sum of the loop voltages appearing acrossresistor 6, resistor 7 and Zener asymmetrically conducting device 18,the bias potential of large current transistor 1 decreases, thus causingless collector-emitter current fiow. Decreased collector-emitter currentflow in transistor 1 results in less load current hence a decrease inload voltage--thus compensating for the original positive increase atthe regulatoroutput terminals. I

Resistor 6 and transistor 2 eliminate the degeneration problem presentedby input voltage variations appearing across biasing resistor 5. Inputvoltage variations appearing across resistor 5 are stepped down by avalue equal to the gain of the stage comprising transistor 2.

Resistors 8, 10 and 14 and Zener asymmetrically conducting device 18provide transistor bias. Capacitor 15 provides low output impedance and,in combination with capacitors 16, 17 and resistor 9, provides highfrequency stabilization against the oscillation etfect inherent indirect-current regulating arrangements with high-loop gain.Asymmetrically conducting device 29 provides con- 3,109,982 j I PatentedNov. 5, 1963 stant bias potentials for transistors 1 and 2 regardless ofload current. This additional bias is necessary for situations where theinput and output potentials approach the same value hence reducing thepotential drop across the biasing resistors to a negligible value.

Zener asymmetrically conducting device 19 is a starting device. At theinstant the input source of potential is applied at the input terminals22 and 23 no voltage appears across the output terminals 24 and 25 sincetransistor 1 is nonconducting as are transistors 2, 3 and 4; Thepotential appearing across the collector-emitter electrodes oftransistor 1 is, therefore, the potential applied to input terminals 22and 23 which may damage the transistor. metrically conducting device 19which breaks down at the instant the source of potential is applied toinput terminals 22 and 23 thereby establishing a base-emitter currentstarting path through transistor 1. Once current flows through the loadthe circuit operates as heretofore described which, in turn, causes thepotential across Zener asymmetrically conducting device 19 to fall to avalue which terminates conduction therethrough.

Since changes may be made in the above-described arrangement anddifferent embodiments may be devised by those skilled in the art withoutdeparting from the spirit and scope of the invention, it is to beunderstood that all matter contained in the foregoing description andaccompanying drawing is illustrative of the application of theprinciples of the invention and is not to be construed in a limitingsense.

What is claimed is:

I. A regulator circuit comprising first and second transistors eachhaving base, collector and emitter electrodes, a pair of input terminalsand a pair of output terminals, one of said input terminals being at ahigher .potential than said other input terminal, means for connectingsaid one of said input terminals to one of said output terminals, meanscomprising the collector-emitter electrodes of said first transistor forconnecting the other of said input terminals to the other of said outputterminals, first and second resistors, means for connecting the emitterelectrode of said second transistor to the collector electrode of saidfirst transistor, means comprising said first resistor for connectingthe base electrode of said second transistor to the collector electrodeof said first transistor, means comprising said second resistor forconnecting the said one input terminal and the collector electrode ofsaid second transistor, means for connecting the collector electrode ofsaid second transistor to the base electrode of said first transistor,means responsive to outputvoltage variations and means for connectingthe base electrode of said second transistor to said output voltageresponsive means.

2. A regulator circuit comprising a detector, an amplifier, atransistorcapable of passing small currents, a transistor capable ofpassing large currents, each of said transistors having base, collectorand emitter electrodes, a pair of input terminals, and a pair of outputterminals, means for connecting one of said input terminals to one ofsaid output terminals, means comprising the collectoremitter electrodesof said large current transistor for connecting the other of said inputterminals to the other of said output terminals, first and secondresistors, means for connecting the emitter electrode of said smallcurrent transistor to the collector electrode of said large currenttransistor, means comprising said first resistor for connecting the baseelectrode of said small current transistor to the collector electrode ofsaid large current transistor, means comprising said second resistor forconnecting the said one input terminal and the collector electrode ofsaid small current transistor, means for connecting the collectorelectrode of said small current transistor of the base electrode of saidlarge current transistor, means for connecting said detector across saidoutput terminals, and

The problem is alleviated by Zener asymmeans comprising said amplifierfor connecting said base electrode of said small current transistor tosaid detector. 3. A negative voltage and current regulator circuitcomprising a detector, an amplifier, a' transistor capable of passingsmall currents, and a transistor capablecf passing large currents, eachof said transistors having base, collector and emitter electrodes, apair of input terminals, a pair of output terminals, means forconnecting one of said input terminals to one of said output terminals,means comprising the collector-emitter electrodes of said large currenttransistor for connecting the other of said input terminals to the otherof said output terminals, first and second resistors, means forconnecting the emitter electrode of said small current transistor to thecollector electrode of said large current transistor, means comprisingsaid first resistor for connecting the base electrode of said smallcurrent transistor to the collector electrode of said large currenttransistor, means comprisingsaid second resistor for connecting the saidone input terminal to the collector electrode of said small currenttransistor, means for connecting the collector electrode of said smallcurrent transistor to the base electrode of said large currenttransistor, means for connecting said detector across said outputterminals, means comprising said amplifier for connecting-said baseelectrode of said small current transistor to said detector, a startingasymmetrically conducting device, means for connecting said startingasymmetrically conducting device across the base-collector electrodes ofsaid large current transistor.

4. A negative voltage and current regulator circuit comprising adetector, an amplifier, a transistor capable of passing large currents,and atransistor capable of passing small currents, each of saidtransistors having base, collector and emitter electrodes, 21 pair ofinput terminals and a pair of output terminals, an asymmetricallyconmeans comprising said second resistor for connecting said one inputterminal to the collector electrode of said small current transistor,means for connecting the collector electrode of said small currenttransistor to the base electrode of said large current transistor, meansfor connecting said detector across said output terminals, and meanscomprising said amplifier for connecting said base electrode of saidsmall current transistor to said detector.

5. A negative voltage and current regulator circuit comprising first,second, third, and fourth transistors each having base, collector andemitter electrodes, first, second,

third and fourth resistors, a pair of input terminals, a pair of outputterminals, first, second, third and fourth asymmetrically conductingdevices, means for connecting one of said input terminals to one of saidoutput terminals, means for serially connecting the other of said inputterminals, the collector-emitter electrodes of said first transistor,said first asymmetrically conducting device, and the other of saidoutput terminals, means for connecting the base electrode of said firsttransistor to the collector electrode of said second transistor, meansfor serially connecting the said one input terminal, said firstresistor, the collector-emitter electrodes of said second transistor andthe said other of said input terminals, means comprising said secondresistor for connecting the base electrode of said second transistor, tothe said other of said input terminals, means comprising said secondasymmetrically conducting device for connecting the baseandcollectorbase electrode of said second transistor, means for connectingthe base electrode of said third transistor to the collector electrodeof said fourth transistor, means for serially connecting the said one ofsaid output terminals, said fourth asymmetrically conducting device, thecollector-emitter electrodes of said fourth transistor, said fourthresistor and the other of said output terminals, an adjustable resistor,means comprising said adjustable resistor for connecting said outputterminals, and means for connecting the base electrode of said fourthtransistor to said adjustable resistor.

6. A negative voltage and current regulator circuit comprising first,second, third and fourth transistors each having base, collector andemitter electrodes, first, second, third, fourth, fifth, sixth, seventh,eighth and ninth resistors, a pair of input terminals and a pair ofoutput terminals, first, second, third and fourth asymmetricallyconducting devices, means for connecting one of said input terminals toone of said output terminals, means for serially connecting the other ofsaid input terminals, the collector-emitter electrodes of said firsttransistor, said first asymmetrically conducting device, and the otherof said output terminals, means for connecting the base electrode ofsaid first transistor to the collector electrode of said secondtransistor, means for serially connecting the said one input terminal,said first resistor, the collector-emitter electrodes of said secondtransistor and the said other input terminal, means for seriallyconnecting the base electrode of said second transistor, said secondresistor, and the other of said input terminals, means comprising saidsecond asymmetrically conducting device for connecting the base andcollector electrodes of said first transistor, means for seriallyconnecting the said one output terminal, said third asymmetricallyconducting device, said third resistor and the said other outputterminal, means for connecting the base electrode of said secondtransistor to the collector electrode ofsaid third transistor, meanscomprising said fourth resistor for connecting the emitter electrode ofsaid third transistor to the junction of said third resistor and saidthird asymmetrically conducting device, first, second and thirdcapacitors, means for serially connecting the base electrode of saidthird transistor,

said fifth resistor, said first capacitor and the said other outputterminal means comprising said sixth resistor for connecting thecollector electrode of said fourth transistor to the said other outputterminal means for connect ing the base electrode of said thirdtransistor to the collector electrode of said fourth transistor, meanscomprising said fourth asymmetrically conducting device for connectingthe emitter electrode of said fourth transistor to the said one of saidoutput terminals, means comprising said seventh resistor for connectingthe emitter electrode of said fourth transistor to the said other ofsaid output terminals, an adjustable resistor, means for seriallyconnecting said one of said output terminals, said eighth and ninthresistors, said adjustable resistor and the said other output terminal,means for connecting said second capacitor across said ninth resistorand means for connecting said third capacitor across said outputterminals.

References Cited in the file of this patent UNITED i STATES PATENTS

1. A REGULATOR CIRCUIT COMPRISING FIRST AND SECOND TRANSISTORS EACHHAVING BASE, COLLECTOR AND EMITTER ELOCTRODES, A PAIR OF INPUT TERMINALSAND A PAIR OF OUTPUT TERMINALS, ONE OF SAID INPUT TERMINALS BEING AT AHIGHER POTENTIAL THAN SAID OTHER INPUT TERMINAL, MEANS FOR CONNECTINGSAID ONE OF SAID INPUT TERMINALS TO ONE OF SAID OUTPUT TERMINALS, MEANSCOMPRISING THE COLLECTOR-EMITTER ELECTRODES OF SAID FIRST TRANSISTOR FORCONNECTING THE OTHER OF SAID INPUT TERMINALS TO THE OTHER OF SAID OUTPUTTERMINALS, FIRST AND SECOND RESISTORS, MEANS FOR CONNECTING THE EMITTERELECTRODE OF SAID SECOND TRANSISTOR TO THE COLLECTOR ELECTRODE OF SAIDFIRST TRANSISTOR, MEANS COMPRISING SAID FIRST RESISTOR FOR CONNECTINGTHE BASE ELECTRODE OF SAID SECOND TRANSISTOR TO THE COLLECTOR ELECTRODEOF SAID FIRST TRANSISTOR, MEANS COMPRISING SAID SECOND RESISTOR FORCONNECTING THE SAID ONE INPUT TERMINAL AND THE COLLECTOR ELECTRODE OFSAID SECOND TRANSISTOR, MEANS FOR CONNECTING THE COLLECTOR ELECTRODE OFSAID SECOND TRANSISTOR TO THE BASE ELECTRODE OF SAID FIRST TRANSISTOR,MEANS RESPONSIVE TO OUTPUT VOLTAGE VARIATIONS AND MEANS FOR CONNECTINGTHE BASE ELECTRODE OF SAID SECOND TRANSISTOR TO SAID OUTPUT VOLTAGERESPONSIVE MEANS.